Large work machines such as on- and off-highway trucks, wheel loaders, graders and track type tractors often employ braking systems in which a recirculating coolant fluid, often oil, is used to absorb and dissipate the heat produced in the brakes during braking action. Oil cooling is common on such vehicles due to their high operating weights and the consequent large amounts of kinetic energy transferred to the brakes as heat during braking.
Fluid-cooled brake components are typically sealed within a housing or casing which contains the coolant around the components. The energy generated in a braking event by these internal components, and energy-related brake operating parameters which can give an indication of brake operation or health, can therefore be described as internal.
Internal brake energy parameters such as internal brake temperature and absorbed brake power (i.e., the kinetic energy absorption rate) can affect component life. Trends of high internal brake temperature may indicate mechanical problems, improper brake use or reduced cooling fluid flow due to leaks in the system or a faulty pump. High brake friction material temperatures also cause premature brake wear and failure. Accordingly, knowledge of internal brake temperature and absorbed power can provide valuable indications of brake operation and remaining brake life. However, it is not practical to directly sense these internal brake energy operating parameters in the internal environment of the brake.